Spatial variation of the temporal clustering properties of non-volcanic tremor activities

Non-volcanic tremor activity is characterized by a variety of recurrence pattern in regions. In this study, we examine the spatial variation of the temporal clustering properties of the tremor occurrence by applying a fractal analysis. By box counting measurement, the temporal distribution of tremor activity in each region exhibits fractal behavior, and its fractal dimension and fractal limit statistically describe the degree of temporal clustering and the recurrence interval, respectively. We analyze the tremor catalogs from Shikoku, southwestern Japan and other tectonic regions in the world. In our result applying into the Shikoku region, the fractal dimension tends to be higher in the up-dip side, yet showing a strong variation along the strike direction of subducting Philippine Sea plate. The recurrence interval positively correlates with locally measured median tremor duration and negatively correlates with the sensitivity to tidal stress.